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and the vessel heated all round : whereas, in those furnaces,where the air passes off by an elbow or chimney atone fide,the action of the fire is chiefly upon one side of the vessel,and consequently, besides an inequality of the heat, a greaterquantity of fuel becomes necessary for producing in the ves-sel the fame degree of heat. The admission of the air by thebottom hole, perpendicularly under the grate, has likewisesome advantage in this respect above the lateral admissionof it by the door.

Instead os the foregoing kinds of vessels, narrowerthan the furnace so as to be received into it, a much broaderone may be placed upon the top, with the three iron sup-porters under it to procure a space for the passage of theair. The flat iron pan, which on other occasions is setunderneath the furnace for receiving the assies, may be usedin this manner as a vessel for calcinations, for the evapora-tion of solutions of lixivial salts, &c.

For vessels of a deeper kind, as a copper still, thecapacity of the furnace is increased by placing over it theiron hoop; by which it is enabled to receive the bodyof a still, of a size sufficient for the purposes of an experi-mental elaborately. In other respects, there is no vari-ation from the preceding form : the fuel is put in throughthe door above the grate ; and the still or other vesselhangs, like the capella or fand-pot, in an iron ring, whichrests upon the three iron supporters placed upon the hoop.

With regard to the distilling vessels, their structure differsfrom that of the large ones in common use. The bodyof the still is a wide copper pan ; and, for distillation in awater bath, another vessel of the fame figure is receivedinto it almost to the top, as represented in the first plate,die space between them being nearly silled with water. Both

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